1. Field of the Invention
The present invention relates to an apparatus and method for resource allocation in a multi-carrier system. More particularly, the present invention relates to an apparatus and method in which a Base Station (BS) allocates consecutive frequency-domain resources to a Mobile Station (MS) in a multi-carrier system.
2. Description of the Related Art
In a multi-carrier system such as a Long Term Evolution (LTE) system, a Base Station (BS) may selectively allocate not only time-domain resources but also frequency-domain resources to a Mobile Station (MS). In doing so, spectral efficiency may be increased by effectively using the time-domain and frequency-domain resources.
Meanwhile, in a case of uplink resource allocation of the LTE system, unlike other multi-carrier systems, there is a restriction in that resources to be allocated to one MS must be consecutive in the frequency domain.
FIG. 1 illustrates an uplink resource allocation method of a BS in an LTE system according to the related art.
Referring to FIG. 1, it is assumed that resource blocks 0 to 7 exist as frequency-domain resources, and the BS allocates the resource blocks to four MSs A, B, C, and D through scheduling. The BS sorts the four MSs A, B, C, and D that participate in the scheduling for each resource block in a descending order according to a channel property. Accordingly, MSs having the best channel property are allocated respectively to the resource blocks 0 to 7 in the order of B, B, A, A, C, A, D, and C.
The BS selects one MS having the best channel property, and allocates a corresponding resource block to the selected MS. Thereafter, among resource blocks adjacent to the allocated resource block, the BS determines whether there is a resource block having the selected MS as the MS having the best channel property. If the resource block exists, the BS additionally allocates the resource block to the selected MS, and if the resource block does not exist, the BS stops the additional resource allocation to the selected MS. Thereafter, the BS allocates resource blocks to the remaining MSs by using the same method.
In FIG. 1, the BS first allocates the resource block 3 to the MS A having the best channel property. Among resource blocks adjacent to the allocated resource block 3, there is the resource block 2 having the MS A as the MS having the best channel property. Thus, the BS additionally allocates the resource block 2 to the MS A. Then, since there is no resource block that has the MS A as the MS having the best channel property among the resource blocks adjacent to the allocated resource blocks 2 and 3, the BS stops the additional resource allocation to the MS A.
Thereafter, the BS allocates the resource block 1 to the MS B having the best channel property among the remaining MSs. Among resource blocks adjacent to the allocated resource block 1, there is the resource block 0 having the MS B as the MS having the best channel property. Thus, the BS additionally allocates the resource block 0 to the MS B. Then, since there is no resource block that has the MS B as the MS having the best channel property among the resource blocks adjacent to the allocated resource blocks 0 and 1, the BS stops the additional resource allocation to the MS B.
Likewise, the BS allocates the resource block 4 to the MS C having the best channel property among the remaining MSs. Since there is no resource block that has the MS C as the MS having the best channel property among the resource blocks adjacent to the allocated resource block 4, the BS stops the additional resource allocation to the MS C, and allocates the remaining resource blocks 5, 6, and 7 to the MS D.
In the resource allocation method having a restriction in that resources to be allocated to one MS have to be consecutive in the frequency domain as described above, there may be a case where not many resource blocks are allocated to an MS having a good channel property, which may lead to a problem of decreasing spectral efficiency. That is, although the MS A has the best channel property among the four MSs that participate in the scheduling in FIG. 1, not many resource blocks are allocated to the MS A. More particularly, although the MS A has the best channel property in the resource block 5, the resource block 5 cannot be allocated due to the restriction of consecutive allocation.